The Rankine cycle or Organic Rankine Cycle (ORC) is a power generation cycle that converts thermal energy to mechanical work. The Rankine cycle is typically used in heat engines, and accomplishes the above conversion by bringing a working substance from a higher temperature state to a lower temperature state. The classical Rankine cycle is the fundamental thermodynamic process underlying the operation of a steam engine.
The Rankine cycle typically employs individual subsystems, such as a condenser, a fluid pump, a heat exchanger such as a boiler, and an expander turbine. The pump is frequently used to pressurize the working fluid that is received from the condenser as a liquid rather than a gas. The pressurized liquid from the pump is heated at the heat exchanger and used to drive the expander turbine so as to convert thermal energy into mechanical work. Upon exiting the expander turbine, the working fluid returns to the condenser where any remaining vapor is condensed. Thereafter, the condensed working fluid returns to the pump and the cycle is repeated.
A variation of the classical Rankine cycle is the organic Rankine cycle (ORC), which is named for its use of an organic, high molecular mass fluid, with a liquid-vapor phase change, or boiling point, occurring at a lower temperature than the water-steam phase change. As such, in place of water and steam of the classical Rankine cycle, the working fluid in the ORC may be a solvent, such as n-pentane or toluene. The ORC working fluid allows Rankine cycle heat recovery from lower temperature sources such as biomass combustion, industrial wasteheat, geothermal heat, solar ponds, etc. The low-temperature heat may then be converted into useful work such as mechanical work that can be put back into the driveline on a vehicle. In other examples it may also be converted into electricity.
The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.